O tratamento de rejeitos de determinados processos industriais vem ganhando importância, seja pelo impacto negativo do simples descarte no meio ambiente, seja pelo valor econômico de materiais e substâncias que podem ser eventualmente recuperados e reciclados. O rápido empobrecimento de reservas minerais primárias e o aumento de demanda de energia são problemas que merecem atenção especial. Neste contexto, a recuperação de metais existentes nos rejeitos de alguns processos de fabricação assume papel de maior importância. A recuperação do molibdênio presente em soluções nitro-sulfúricas, na forma de rejeitos líquidos do processo de fabricação de lâmpadas incandescentes e fluorescentes, não constitui exceção no que diz respeito à importância da reciclagem. Este rejeito, proveniente da dissolução dos mandris de conformação dos filamentos de tungstênio das lâmpadas, apresenta valores que podem ser recuperados e até reciclados no próprio processo. É o caso dos ácidos nítrico e sulfúrico. Já o molibdênio, presente em concentrações em torno de 40 a 90 g.L-1, pode ser recuperado e utilizado na fabricação de aços especiais, pigmentos, lubrificantes, adubo, etc. Neste trabalho foram desenvolvidos dois processos de recuperação deste rejeito. No primeiro, o rejeito é diluído e por cromatografia de troca iônica o molibdênio é recuperado. Os ácidos efluentes são destilados para a retirada da água. No segundo processo, o rejeito passa por uma destilação e ao mesmo tempo o molibdênio é precipitado. Em ambos os processos, os ácidos recuperados podem voltar à fábrica de lâmpadas para a dissolução dos mandris do filamento de tungstênio e o molibdênio encontra outras diferentes aplicações, além de possuir um valor significativo no mercado. / The waste treatment of certain industrial processes is becoming more important, either by the economic impact of simple disposal in the environment, or by the economic value of materials and substances that can eventually be recovered and recycled. The rapid depletion of mineral reserves and increasing primary energy demand are problems that deserve special attention. In this context, the recovery of metals present in waste of some manufacturing processes assumes a great importance. The recovery of molybdenum present in nitro-sulfur solutions in the form of liquid waste in the manufacturing process of incandescent and fluorescent lamps, is no exception with regard to the importance of recycling. The tailing from the dissolution of the molybdenum mandrel wires used in the conformation of the tungsten filament of electric lamps, has values that can be recovered and recycled to the process itself. Is the case of sulfuric and nitric acids. Molybdenum, present in concentrations around 40 to 90 g.L-1, can be recovered and used in the manufacture of special stainless steel, pigments, lubricants, fertilizer, etc.. In this work two processes for the recovery of this waste were proposed. At the first one, the waste is diluted and molybdenum is recovered by ion-exchange chromatography. The effluent acid from this process was distilled to extract water used in the dilution step. In the second case, the waste goes through a distillation while the molybdenum is precipitated. In both cases, the acids are recovered back to the lamp factory for the dissolution of the molybdenum mandrel wires and molybdenum finds other different applications, as well as having significant value in the market.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2016. / The main purpose of this study is to understand the application of ion exchange chromatography on separation of charged ions of elements. Ion exchange chromatography is an analytical method, which is used for the separation of elements, quantitation and qualitation. The use of Amberlyst 15 resin as a source of separation for metal ions has been investigated and studies in various academic disciplines such as chemistry and material science. In this research study, Amberlyst 15 resin was investigated in order to understand the separation of positively charged divalent elements ions (Zn2+, Cu2+, Co2+ and Ni2+). The use of nitric acid and methanol mixture enhanced separation of these metal ions by ensuring that nitric acid is constant and varying methanol concentration. In this study, it was found that the resin has a high affinity for the metal ions at high methanol concentration, hence the distribution coefficient values increase but decreases at low methanol concentrations. The complexities of molecular structure of the salts of the elements provide the more understanding of the metal ion interaction with the resin particle. Furthermore, the role and strength of nitric acid to break the structural bonds and release the metal ions to get sorbed on the resin remains the most essential factor of understanding distribution coefficient values. Method validation parameters such as linearity, precision and accuracy of the method were determined. The method precision and accuracy were determined from the QC samples which is expressed as relative error (%RE) with the total coefficient of variation (%CV’s) were < 20%.

Graduation date: 1999

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Abraham M. Lenhoff, Dept. of Chemical Engineering. Includes bibliographical references.

Thesis (Ph.D.(Chemistry))--University of Pretoria, 2004. / Summaries in English and Afrikaans. Includes bibliographical references (leaves 229-238). Also available online.

S-Adenosylmethionine (SAM) synthetases isolated from both the yeast and hyphal-phase of the dimorphic fungus, C. albicans, were partially purified using DEAE cellulose ion-exchange column chromatography. Further characterization was accomplished using enzyme kinetics and specific enzyme effectors. SAM synthetase is the enzyme responsible for synthesis of SAM which is the major methyl group donor in the methylation of macromolecules. Kinetic studies on column samples, from both phases, were performed. The yeast-phase enzyme had apparent Km ranges for L-methionine and ATP of 1.06-1.42mM and 1.11-1.69mM, respectively. The hyphal-phase enzyme had apparent Km ranges for L-methionine and ATP of 1.34-2.66mM and 3.29-6.28mM, respectively. Effector studies (in vitro) indicate that 10% (v/v) dimethyl sulfoxide (DMSO) and 5mM cycloleucine inhibit SAM Synthetase from both phases, 24% and 46%, respectively. The methionine analogues DLmethionine sulfone, DL-methionine-DL-sulfoxide and L-methioninesulfoximine and sinefungin, an analog of SAM, had no effect on SAM synthetase activity. Although the data is inconclusive with respect to the existence of isozymes, the observed Km's of the yeast and hyphal-phases are different suggesting that isozymes may exist. Additionally, the yeast-phase DEAE column profile has a shoulder prior to the main peak of activity indicating that more then one form of the enzyme may be present. / Department of Biology

Graduation date: 1994

Bibliography: leaves 225-230. / xxi, 235 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis investigates the scale-up of an ion-exchange chromatographic system to manufacture whey growth factor extract (WGFE) from cheese whey. Key scale-up problems are identified and discussed. Alternative scale-up methodologies required to overcome several of these problems are considered. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1997?

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